The UK prime minister reportedly pressed Tusk over the issue in early April, more than a fortnight before the prime minister called for a general election.

May later raised the issue with EU Commission President Jean-Claude Juncker during a Downing Street dinner on Friday (28 April). The prime minister apparently wanted to settle the issue as early as June.

But the Conservative premier has been publicly rebuffed by Brussels, with a detailed account of the summit with Juncker being leaked to the German press. The EU chief also reportedly phoned German Chancellor Angela Merkel to claim that May was living on "another galaxy" when it came to Brexit.

May initially dismissed the reports as "Brussels gossip", but last night upped the ante and promised to be a "bloody difficult woman" during the two-year-long talks.

The EU, meanwhile, is planning to raise its divorce bill from €50bn (£42bn) to €100bn, according to The Financial Times. The revised bill is apparently being pushed by Germany and France.